Wind Deflector

[Flyfisher]

Hi Folks - This is the wind deflector that I built. Didn't use the rack bars, just mounts and clips. Took a while to find right combo of PVC fittings and bar that would work. Works great so far. Had it in gomething like 100 mph of wind and it stayed on. Don't know about MPG since I didn't have numbers from before, but it sure does take care of turbulance between cab and camper. Still working on how to reduce windage of front sides of Hawk. This site has some interesting info for the nerds among us. http://ecomodder.com/forum/showthread.php/full-boat-tail-trailer-gap-fillers-toyota-t-7839-25.html Page down about halfway for some drawings with drag coefficients. Hope this helps.

 

[Flyfisher]

Here is that site again. The first one didn't seem to work. http://ecomodder.com/forum/showthread.php/full-boat-tail-trailer-gap-fillers-toyota-t-7839-25.html
I hope that this one works.

 

[ETAV8R]

Very nice Flyfisher.
I'm sure your mileage is better. What material is your fairing made of?

 

[Cerdahl]

Flyfisher
That's fantastic. You should sell your design for the big bucks!

 

[takesiteasy]

Yeah, I like the idea of ditching the rack bar and just using the towers. Also curious what material you used for the fairing.

 

[Cerdahl]

Paul, I might, I'll go up to the barn on Friday and see what I've got, then I'll send you a PM.

Alley-Kat
Is that sign material PVC? A friend works at a sign place and he thinks its from 6mm sheeted PVC. Is that rigid/strong enough to make a larger one to sit on a rack? If not, I could laminate two sheets together to beef it up. What do you think?

 

[Alley-Kat]

I've not built one of the large flat air fairings, so, I'm not really your expert on this, however, 6mm is almost 1/4" thick (0.23622" to be exact), so it could be thick/rigid/strong enough for the large flat wind fairings that most of the guys have built. And, I suppose if you got any vibrations or humming from driving at highway speeds you could always laminate another sheet on top of the first sheet.

I actually don't know what material it is, but, it could be PVC, it's doesn't seem to be acrylic or plexiglass. Back in 1997 when my wife opened her business, we just gave the sign design to a sign shop and they made it and installed it, and I paid for it... and I recycled the signs when she closed the business.

I sent you a PM about the questions you asked me via PM.

 

[Cerdahl]

Thanks Alley-kat
That's good, helpful info. Since the sign plastic is often so thin now, I'll be forced to laminate a bunch. I saw a large deflector online made from sheet aluminum. Very easy to work with and stands up to the wind.
Thanks

 

[Flyfisher]

The fairing is 5/8 T-111 plywood house siding. (Use what you got sitting around) It is a bit heavy. Could probably go to 1/2 inch. Wanted to make sure that it was safe and wouldn't deflect at 70+ mph. I wanted wood because I knew that it could handle flexing w/out breaking. What I had heard about plexiglass scared me. If all or part of the deflector flew off at highway speeds, it could kill someone. I did some testing on back roads before I took it on the Freeway. Biggest expense was the used Yakima racks. I would love to find a stiff and light inexpensive material to replace the plywood with. Of course, the best option is to have it mounted to the camper rather than the truck, but I haven't quite figured that out. It was a fun project, but it did take a little time and it certainly can be improved. This site provided the inspiration. Thanks to all the people that posted pictures of their wind deflectors.
Cerdahl - Thought about it briefly (I am pretty proud, having designed it from scratch) but then realized that each truck camper combo is different. And then there is the liability issue.

 

[Dusty]

This guy 'Sleepy' at rv.net has a detailed thread on his deflector he put on his setup (he's got a Lance).
here-- http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/17575645.cfm

A post from Sleepy on his thread (only $20 spent):
As you apparently recognize the airfoil does more than eliminate bugs on the bulkhead. It gently moves the air that normally gets caught under the cabover to the outside along with the bugs... it also eliminates much of the drag that is associated with that area.

We found that over more than 10000 miles we have had about a 10% increase in fuel economy.... about 1 1/2 miles/gal.

Our lifestyle also contributes to decent fuel economy.... we seldom exceed 63 mph. Doing engineering studies our optimun speed would be about 48 mph... up to 48 mph the fuel is expended in pulling the weight of our rig, above 48 mph the drain on fuel economy is drag... and our drag is based on pushing an area 8' wide and 11 foot tall. At speeds of 70mph our fuel effiency drops a third. At 80 mph to 1/2.

Every little bit of drag eliminated counts. The airfoil works simply and well... for a couple of hours work and less than $20 in materials.

Now to lower the drag on the back of the camper!

 

[Cerdahl]

Flyfisher
You are right about the liability issue. I wouldn't want my mod hurting someone or causing damage.

 

[Bosque Bill]

If anyone is ready to buy new stock roof rack parts for a deflector, REI is advertising 20% off all Thule and Yakima from Aug 23 - Sept 2.

 

[Cerdahl]

Thanks, I still might make one.

 

[Kodachrome]

I love my homemade deflector, constructed out of aluminum on a Thule rack, it now holds a 40 watt 3 pound flex panel and the whole thing comes off in a couple of minutes. I know it is saving me gas and the wind turbulence has been *much* reduced...